Introduction:

Venous Thromboembolism (VTE) remains a serious threat after Total Knee Arthroplasty (TKA), a crucial orthopedic procedure. With an annual rate of over 2.8 million TKA surgeries in the United States. Despite improvements in surgery and thromboprophylaxis, patients are still vulnerable to VTE due to factors like endothelial damage and hypercoagulability. While VTE rates were once as high as 20% in the 1970s, they have dropped to about 1% due to better preventive measures. However, VTE remains concerning due to its associated risks and healthcare costs. Managing complications like pulmonary embolism (PE) and deep vein thrombosis (DVT) emphasizes the need for ongoing research to optimize prevention and patient outcomes.^[1]

Prevalence and Incidence:

Thanks to consistent and crucial prophylaxis for venous thromboembolism (VTE), there has been a remarkable decrease in VTE rates over the years. From a concerning 20 percent in the 1970s, the current rate stands at a mere 1 percent, showcasing a significant downward trend. This decline is substantiated by analyses of the ACS-NSQIP database. Various studies focusing on total knee arthroplasty (TKA) until 2016 have consistently demonstrated a steady decrease in deep vein thrombosis (DVT) rates. For instance, Sarpong et al., utilizing the NSQIP database from 2006 to 2016, reported a 30-day DVT rate following TKA of 0.87%, showcasing a decline from 1.5% between 2006 and 2009 to 0.79% between 2014 and 2016. Similarly, Warren et al. analyzed data and identified an overall 30-day venous thromboembolism (VTE) rate of 1.4%, inclusive of a DVT rate of 0.9% and a pulmonary embolism (PE) rate of 0.6%. This rate decreased notably from 3.0% (DVT 2.2%, PE 1.0%) in 2008 to 1.4% (DVT 0.9%, PE 0.6%) in 2016, indicating a significant temporal shift towards improved outcomes.^[1]

Clinical Significance:

Extensive research underscores the profound impact of venous thromboembolisms (VTEs) on mortality and morbidity. Literature across numerous studies consistently highlights how VTEs not only prolong hospital stays but also exacerbate complications such as infections stemming from prolonged hospitalization. Furthermore, specific emphasis is placed on the association between VTEs, particularly pulmonary embolisms (PEs), and heightened mortality rates, as indicated by various publications. This collective body of evidence underscores the critical importance of addressing VTEs comprehensively to mitigate their adverse effects on patient outcomes and healthcare system burdens.^[1]

Risk Factors:

Demographic Factors:

Age, gender, and race play pivotal roles in determining the thrombogenicity of patients undergoing Total Knee Arthroplasty (TKA). Research spanning numerous studies has consistently highlighted the influence of these demographic variables on VTE risk post-TKA. Gender, for instance, has been a subject of debate, with some studies suggesting a higher risk of deep vein thrombosis (DVT) in females compared to males. Variations in hormonal profiles, clotting factors, and genetic predispositions between genders may contribute to this disparity. Additionally, advancing age is a well-established risk factor for thrombosis formation, with elderly patients often exhibiting increased susceptibility to VTEs post-TKA. Moreover, racial disparities in VTE risk have been observed, with individuals of African ancestry demonstrating a higher predisposition compared to other racial groups. Conversely, Asian populations tend to exhibit lower rates of VTE, attributed to both clinical under-recognition and genetic factors.^[1]

Cardiopulmonary Status:

The cardiopulmonary status of patients undergoing TKA significantly influences the occurrence of VTEs. Preexisting conditions such as chronic obstructive pulmonary disease (COPD) and congestive heart failure (CHF) have been identified as critical risk factors for VTEs post-TKA. Patients with COPD face an elevated risk of DVT, while CHF predisposes individuals to pulmonary embolism (PE), aligning with the pathophysiology of PE.^[1]

Preoperative Mobilization Status:

Preoperative mobilization status serves as a significant indicator of VTE risk following TKA. Patients who are partially or fully functionally dependent or require active support face challenges with mobility, leading to prolonged periods of immobilization and increased DVT risk post-TKA. Similarly, functionally dependent patients and those needing ventilatory support are predisposed to PE due to challenging mobilization. Early ambulation programs and physical therapy interventions are essential to mitigate these risks among vulnerable TKA patients.^[1]

Malignancy:

Malignancy status also influence VTE risk post-TKA. Individuals with a history of malignancy face increased risks of postoperative DVT and PE, with active malignancies presenting higher complication rates.^[1]

Prevention:

The prevailing guidelines governing Venous Thromboembolism (VTE) prophylaxis post-arthroplasty are established by the American College of Chest Physicians (ACCP) and the American Academy of Orthopaedic Surgeons (AAOS). As per the ACCP's 2012 guidelines, pharmacologic prophylaxis is advocated for both Total Hip Arthroplasty (THA) and Total Knee Arthroplasty (TKA). Notably, Grade 1B recommendations endorse the use of various agents, encompassing low molecular weight heparin, fondaparinux, dabigatran, apixaban, rivaroxaban, unfractionated heparin, vitamin K antagonists, and aspirin, administered for a minimum of 10–14 days and up to 35 days. Emphasis is placed on low molecular weight heparin over alternative agents, based on a Grade 2C/2B recommendation. Conversely, the AAOS recommends pharmacologic prophylaxis for THA and TKA, contingent upon patients lacking heightened bleeding risks, without specifying particular agents. In clinical practice, orthopedic surgeons are tasked with meticulously balancing the potential for adverse events associated with potent pharmacologic agents against the prophylaxis benefits, while considering each patient's unique risk profile for VTE.^[2]

Challenges with Current Guidelines:

A notable critique of existing guidelines is their inability to provide recommendations tailored to individual patients. Despite global improvements in provider adherence to guidelines, there remains room for enhancement. Enhancing individualized advice within guidelines could potentially further improve adherence rates.

Prescription Patterns:

Prescription trends indicate a shift towards increased aspirin use for VTE prophylaxis post-TKA. Studies report varying prescription patterns across different regions and timeframes, with aspirin emerging as a popular choice alongside other pharmacologic agents. However, discrepancies exist in adherence rates to prophylaxis protocols.

Efficacy and Safety of Aspirin:

The efficacy and safety of aspirin for VTE prophylaxis have garnered increasing attention. Meta-analyses suggest comparable efficacy between aspirin and other pharmacologic regimens, with reduced risks of bruising and lower extremity edema but no significant difference in bleeding, infection, or mortality rates. Notably, aspirin has demonstrated effectiveness even in high-risk scenarios and among specific patient groups.

Optimal Dosing and Additional Benefits:

Optimizing aspirin dosage remains crucial for its efficacy, with studies indicating similar outcomes between low-dose (<162 mg/day) and high-dose (>162 mg/day) aspirin regimens. Research also explores potential additional benefits of aspirin, including its role in reducing heterotopic ossification after THA and its combination with fish oil for VTE prevention.

Patient Adherence to Regimens:

The efficacy of VTE prophylaxis heavily relies on patient adherence post-TKA. Once-daily oral medications, such as aspirin, exhibit better adherence rates compared to twice-daily regimens. Nonetheless, patient adherence to medication regimens remains suboptimal, suggesting the need for strategies to improve compliance.

Conclusion:

In conclusion, addressing the multifaceted challenges associated with VTEs in TKA requires a comprehensive approach encompassing evidence-based guidelines, personalized patient care, and strategies to enhance adherence to preventive measures. By continually refining preventive strategies and optimizing patient management, healthcare professionals can strive towards minimizing the burden of VTEs and improving the overall quality of care for TKA patients.